In Situ TEM-STM Recorded Kinetics of Boron Nitride Nanotube Failure under Current Flow

Joule-heating-induced failure of individual multiwalled boron nitride (BN) nanotubes is investigated in a high-resolution transmission electron microscope (TEM) equipped with a scanning tunneling microscope (STM) unit. Direct observation of the failure process indicates that it occurred via thermal decomposition of tubular layers from inside-out of a tube leaving amorphous ball-like boron-based nanoparticles behind. The electrical transport is well simulated by the thermionic field-emission model. The thermal decomposition temperature, which is deduced from a breakdown curve, shows a dependence on local electrical field; the higher the electrical field, the lower the decomposition temperature. This is attributed to partially ionic nature of a B-N bond.